Mode Mismatch Causes “Hyperloss” of Up to 30% in Quantum Networks

A seemingly small misalignment of light beams in quantum networks can trigger a disproportionate loss of quantum information, with researchers now demonstrating up to 30% relative to the initial squeezing, a phenomenon they term “hyperloss.” Stephan Grebien, Julian Gurs, Roman Schnabel, and Mikhail Korobko of Universität Hamburg report that even 1% mode mismatch within a two-node quantum network was enough to convert a squeezed state into an effectively thermal state with no quadrature squeezing, effectively eliminating any quantum advantage. This finding challenges the standard assumption that such mismatches cause only minor, incoherent loss. The team’s work reveals that hyperloss arises from quantum-correlated mixing…